Camshaft retainers with as-pressed windage relief holes and a method of making the same

ABSTRACT

A high-performance camshaft retainer having a plurality of windage relief holes embodying an as-pressed configuration and a method of manufacturing the same, wherein the windage relief holes are molded from a powdered metal matrix and provided in an as-molded detail.

BACKGROUND OF THE INVENTION

The present invention relates to camshaft design and, more particularly, a high-performance camshaft retainer embodying a molded light configuration and a method of manufacturing the same, wherein the retainer holes are molded from a powdered metal matrix, resulting in a lightweight steel retainer with as-pressed windage relief holes.

High-performance camshafts in internal combustion engines require enhanced valve-train upgrades to maximize the performance of the camshaft design, since at a rate of 75 cycles/second the closed face of conventional retainer designs create considerable compressed air trapped under the retainer during the valve-train travel, resulting in windage that can lead to oil foaming and chemical breakdown of the lubricating oil.

High-performance camshaft design requires a high-strength retainer with a plurality of spaced apart holes dimensioned and adapted for the task at hand. Currently, the holes in the retainer have only been available as a machined feature. Due to the cost of drilling each hole and the number of holes, however, the machined approach is not cost effective. For instance, machining of lightweight steel retainers requires compromised cross-sections that can lead to failure. Moreover, using exotic high-strength, lightweight material, like Titanium or MMC, for machining retainer holes is prohibitively expensive for a high-volume business case.

As can be seen, there is a need for a high-performance camshaft retainer embodying a molded light configuration, wherein the retainer holes are molded from a powdered metal matrix. The molded holes create passages to vent compressed air through the retainer during valve-train cycling, while the lightweight aspect of the retainer allows for reduced valve spring pressures resulting in the improvement of valve control and engine efficiency with a low manufacturing cost compared to a fully machined counterpart.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a valve spring retainer includes a plurality of relief holes in an as-pressed condition.

In another aspect of the present invention, the above-mentioned valve spring retainer wherein the plurality of relief holes is molded from a powdered metal matrix, wherein each relief hole of the plurality of relief holes are spaced apart in a radial manner inward of an outward periphery and outward of an inner periphery, and wherein the inner periphery defines a central tapered opening.

In yet another aspect of the present invention, a method of reducing valve spring pressures and manufacturing cost compared to a fully machined counterpart, the method includes: molding a valve spring retainer as a powdered metal blank with a plurality of relief holes in an as-pressed condition; sintering and machining a bottom portion of the valve spring retainer for defining a one or more spring locating contours; heat treating the valve spring retainer; and replacing a pre-existing valve spring retainer and installing the valve spring retainer, wherein the one or more spring locating contours are configured to operatively associated with a spring package configuration of the pre-existing valve spring retainer.

It should be understood that the camshaft retainer 10 shown in the Figures and described in the below specification may also be referred to as the valve spring retainer 10.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of the present invention, shown in use, with parts shown in cross-section;

FIG. 2 is a perspective view of an exemplary embodiment of the present invention;

FIG. 3 is a side elevation view of an exemplary embodiment of the present invention;

FIG. 4 is a top plan view of an exemplary embodiment of the present invention; and

FIG. 5 is a cross-sectional view of an exemplary embodiment of the present invention, taken along line 5-5 in FIG. 4 .

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Broadly, an embodiment of the present invention provides a high-performance camshaft retainer having a plurality of windage relief holes embodying an as-pressed configuration and a method of manufacturing the same, wherein the windage relief holes are molded from a powdered metal matrix and provided in an as-molded detail.

Referring now to FIGS. 1 through 5 , the present invention includes a camshaft retainer 10 having windage relief holes 16 in an as-molded detail 12, and a method of making the same. The camshaft retainer 10 may be placed in contact with a lock element 18, such as a tapered split lock or a valve lock, via a central tapered opening 14 around a central shaft or valve stem 11 at a distal end thereof. Typically, the camshaft retainer 10 is operatively associated with a rocker arm (not shown). The central shaft or valve stem 11 may have a valve stem seal 22 along a proximal end thereof. The camshaft retainer 10 may have a constant upward pressure from one or more valve springs 20.

The windage relief holes 16 may be spaced apart in a radial manner about the camshaft retainer 10, wherein the windage relief holes 16 are radially disposed between the central shaft or valve stem 11 and the one or more valve springs 20.

The windage relief holes 16 reduce the total mass of the camshaft retainer 10, allowing for a quicker and more accurate reaction of the spring during rapid valve-train actuation. In addition to the mass reduction of the above-mentioned molded light configuration, wind resistance, as an additional force for the spring(s) 20 to overcome, is also diminished. Thereby, the present invention enables manufacturing cost effect high-performance camshaft retainers 10 for more accurate valve control with aggressive valve actuation, without increasing spring pressure.

A method of manufacturing the present invention may include the following. The retainer 10 may be molded as a powdered metal blank with the windage passages 16 and top profile in an as-pressed condition. The part may then be sintered and machined for the spring locating contours via a machined bottom profile 24. This is followed by heat treatment. The same powdered metal blank may be machined in numerous spring package configurations.

Machining the blank in multiple configurations is optional. Exotic materials would be beneficial for strength, but not required for the loads in the designed application and do not impact the windage benefit. The shape and number of the windage passages 16 could be changed. An alternate powdered metal recipe/blend or heat treat could be employed.

A method of using the present invention may include the following. The high-performance camshaft retainers 10 disclosed above may be provided. A user may remove heavier retainers and replace with the powdered metal mold windage passages retainer 10 to improve valve-train actuation accuracy resulting in increased longevity of springs 20 and power output due to efficiencies gained by the reduced mass and windage relief enabled by the present invention.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A valve spring retainer, comprising a powered metal and a plurality of relief holes in an as-pressed condition and configured to reduce wind resistance.
 2. The valve spring retainer of claim 1, wherein the plurality of relief holes is molded from a powdered metal matrix.
 3. The valve spring retainer of claim 2, wherein each relief hole of the plurality of relief holes are spaced apart in a radial manner inward of an outer periphery of the valve spring retainer and outward of an inner periphery of the valve spring retainer.
 4. The valve spring retainer of claim 3, wherein the inner periphery defines a central tapered opening.
 5. A method of reducing valve spring pressures and manufacturing cost compared to a fully machined counterpart, the method comprising: molding a valve spring retainer as a powdered metal blank with a plurality of relief holes in an as-pressed condition.
 6. The method of claim 5, further comprising sintering and machining a bottom portion of the valve spring retainer for defining one or more spring locating contours.
 7. The method of claim 6, further comprising heat treating the valve spring retainer.
 8. The method of claim 7, further comprising replacing a pre-existing valve spring retainer and installing the valve spring retainer, wherein the one or more spring locating contours are configured to be operatively associated with a spring package configuration of the pre-existing valve spring retainer. 